general info about graphic scores: http://en.wikipedia.org/wiki/Graphic_notation

"In the late forties and early fifties it became clear that there is a correspondence between time and space. And music is not isolated from [space], because one second of sound is so many inches on tape. That means that the old meters of two, three, and four are no longer necessary, that space on a page is equivalent to time. Therefore, I began doing graphic notations, and those graphic notations led other people to invite me to make graphic works apart from music. And those led me in turn to make musical scores that were very graphic."

-john cage

and 'eye music': http://en.wikipedia.org/wiki/Eye_music